As a core technology of a next generation transport network, an optical transport network (Optical transport network, OTN) has abundant Operation, Administration and Maintenance (OAM), strong tandem connection monitoring (TCM) and out-of-band forward error correction (FEC) capabilities, can implement flexible scheduling and management of a high-capacity service, and gradually becomes a mainstream technology of a backbone transport network.
An OTN frame is a 4080*4 modular structure and can carry a client signal. An optical channel data unit-flex (Optical Channel Data Unit-flex, ODUflex) is an OTN frame corresponding to a new rate level, and can carry services with different rates. During service transmission, the service is first mapped to a payload region of the ODUflex, and then the ODUflex is mapped to a high order optical channel data tributary unit-k.M (HO ODTUk.M), where M represents that the ODUflex occupies M time slots of the high order optical channel data unit-k (HO ODUk).
An OTN service carrier includes an OTN symmetric bandwidth carrier and an asymmetric bandwidth carrier. As for an OTN symmetric bandwidth carrier system, in upload and download directions, the number of time slots (Time Slot, TS) occupied by the ODUflex of encapsulating service and TS allocation condition are consistent; while as for the OTN asymmetric bandwidth carrier system, upload and download bandwidths of the carrier service are inconsistent.
For example, in a point-to-point OTN symmetric bandwidth carrier system shown in FIG. 1, a service passes through two intermediate nodes A and B from a source node to a sink node, and the channel is formed by three link (Link) segments and two cross matrix connection (Matrix) segments. During packet service transmission, the source node maps the packet service to the ODUflex, and maps the ODUflex into HO ODTU2.2 (the ODUflex occupies TS1 and TS4 of HO ODU2) , the node A maps the ODUflex to HO ODTU3.2 (the ODUflex occupies TS5 and TS12 of HO ODU3) after the ODUflex is crossed by the node A, and then the node B maps the ODUflex to HO ODTU2.2 (the ODUflex occupies TS4 and TS5 of HO ODU2) after the ODUflex is crossed by the node B, and finally the sink node de-maps the packet service from the ODUflex. In the direction from the sink node to the source node, the packet service is transmitted according to the same bandwidth distribution.
Since the service traffic flow has a demand of non-real time dynamic change, the ODUflex needs to provide different bandwidths in different periods to meet the change demand of the traffic flow. With the increasing of the OTN carrier services, the asymmetric bandwidth services such as a Gigabit-capable passive optical network (Gigabit-Capable Passive Optical Network, GPON) and video on demand (Video On Demand, VOD) also increase. However, in the prior art, lossless adjustment is not performed on the OTN asymmetric bandwidth carrier, which cannot meet the change demand of the asymmetric bandwidth service traffic flow.